Gunning For A Fight
Two chicks hatch; only one will survive. Nazca boobies on the Galápagos Islands often lay two eggs, but there's rarely enough food for two nestlings. The birds avoid this problem with a fight to the death soon after birth. Now a study led by Wake Forest University reveals what prepares chicks for battle: high levels of testosterone and other hormones that promote aggression.

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A Sideways Glance
Even Darwin floundered to explain flatfish like sole and halibut. Sure, having both eyes on the same side of your head is helpful if you lie on the ocean floor, but how does such a strange gaze evolve? Fossils from 50 million years ago, newly analyzed by a University of Chicago researcher, show that a flatfish ancestor had one eye in a normal position and one near the top of its head, a transition to its modern form.

ObservedName: Agamid lizards living in Australia.Walk: On all fours.Run: On their hindquarters, at least in some species.Confound: Attempts to ascertain why, in evolutionary terms.Submit To: Treadmill running and high-speed video recording.Which Yield: Data suggesting that species that run bipedally do so because they are...popping wheelies. Species with heavy hindquarters are most susceptible to having their front quarters lift off the ground during rapid acceleration, according to researchers in Australia. No evolutionary advantage was evident.

Floral Flirtation
Flowers sway in the breeze to beckon pollinators, a study from Wales' Aberystwyth University suggests. Sea campion plants
with slim stems fluttered the most and attracted the most insects. (Flowers with average stems set the most seeds though, apparently because pollinators visited more stable flowers longer.) The study is the first evidence that "waviness," like color and scent, influences a flower's attractiveness.

Time to Get Cracking
The sound that Nile crocodile embryos make shortly before hatching is not just baby talk. Scientists in France played recordings of the "umph! umph!" calls to croc mothers and egged siblings; the moms dug up their nests and the babies got cracking. Synchronized hatching may minimize the nest's exposure to predators.